Problem: Simplify the following expression: $2\sqrt{45}$.
Solution: First, try to factor a perfect square out of the radical. $= 2\sqrt{45}$ $= 2\sqrt{9 \cdot 5}$ Separate the radical and simplify. $= 2\sqrt{9} \cdot \sqrt{5}$ $= 2 \cdot 3 \cdot \sqrt{5}$ $= 6\sqrt{5}$